1. Field of the Invention
The present invention generally relates to a redundant system for devices with network capability and a method for the same. More particularly, the invention is to establish a redundant connection for the networking devices by defining the roles of ports for each network node.
2. Description of Related Art
Since network applications are widespread, it is more important to provide a safe and reliable network environment. In order to prevent the network from interruption made by any unexpected event, or broken connection subject to any network device's failure, some conventional technologies have provided the redundant mechanisms for every type of network.
Reference is made to FIG. 1, which shows a framework of a conventional linear-type network. A user computer 101 connects to a remote network device via network 10. The remote network device may be one or more industrial control machines 103, 104, which are used to control various terminal devices. The industrial control machine 103 is connected to the network 10 through a network switch 102, and the machine 104 is through a network switch 105. Under this simple framework, the connection 1 or connection 2 provides no any redundant mechanism. If the connection 1 or connection 2 meets any interruption event, the user computer 101 may not access any one of the industrial control machine 103, 104 via the network 10. One the other hand, if any device on the connection 1 fails, for example, the network switch 102 is caused damage, the user computer 101 likely fails to access the industrial control machine.
With respect to network connection, the often-seen redundant scheme is to provide a redundant network connection besides the original connection. In the current example, the connection 1 and the connection 2 are mutually redundant connection. Further, any terminal device simultaneously has two outward connections (1, 2) through the industrial control machines 103 and 104. If the original connection 1 meets any problem, the connection 2 may take over the connection in order to accomplish the redundant connection. Therefore, the various networking behaviors may not be influenced.
With respect to the network devices, such as a router or a switch, many computers' network connections may be influenced if any device fails. Reference is made to FIG. 1, if the network switch 102 connected to the industrial control machine 103 fails, the user computer 101 may use the network switch 105 on the connection 2 to control the terminal device. Meanwhile, two or more networking devices may achieve the redundant connection.
In addition to the above-described redundant schemes using the various connections or network devices, other conventional technologies may perform the redundancy through various topologic designs of networks. Such as a bus network, two connections are adopted for performing the redundancy. For a ring network, the ring-type connection may provide its own redundant mechanism. For a start network, a mesh network accomplishes the redundancy by various routing schemes.